Ferrous alloys and articles made therefrom



United g FERROUS ALLOYS AND ARTICLES MADE THEREFROM David P. Hughes,Ligonier Township, Westmoreland County, and Stewart G. Fletcher,Latrobe, Pa, assignors to Latrobe Steel Company, Latrobe, Pa., 21corporation of Pennsylvania No Drawing. Filed Mar. 28, 1958, Ser. No.724,503

8 Claims. (Cl. 75'126) This invention relates to ferrous alloys and inparticular to ferrous alloys having peculiarly advantageous propertiesfor use in hot work applications in theforming of extremely hard anddiflicult to forge materials and in applications where dimensiontolerance is important. There has long been a need for a steel capableof withstanding the stresses and wear problems encountered in certainhot work applications, such as dies for forging extremely hardmaterials, as, for example, the super alloys used for hightemperatureservice in jet engine parts, gas turbine parts and the like. There hasalso been a need for an alloy capable of withstanding the erosionencountered in extruding aluminum, brass and magnesium, as well as indie casting and other hot work applications. The steels normally usedfor this service have a relatively short life and consequently the dieexpense per forged piece is high. Not only is die cost high in suchapplications but the lost time and labor involved in replacing dies is avery significant pant of the cost of each part produced.

We have discovered an alloy having surprisingly advantageous propertiesfor use in the applications mentioned hereinabove. We have found analloy which is deep hardening and non-deforming and will maintain itsform and tolerance dimensions under the extreme conditions encounteredin die forging the superalloys, as well as in extruding materials suchas aluminum, brass and magnesium. We have also discovered that the alloyis relatively easy to form and yet has great impact strength andresistance to dimensionchange in use.

We have found that the preferred composition of our alloy is Percent C1.10 V 4.0 Mn 0.40 Cr 5.25 Mo 1.10

Balance substantially iron with residual impurities in ordinary amounts.

The composition of our alloy may, however, extend over a wider range andinclude other elements while still retaining its peculiar and highlydesirable properties. In every case, however, the alloy must containcarbon, vanadium, chromium and molybdenum within the limits set outhereinafter in order to retain these desirable and peculiar properties.The broader composition may fall within the limits of ice Balancesubstantially iron with residual impurities in ordinary amounts, inwhich alloy the vanadium shall appear in amounts within the foregoinglimits that vanadium 1 Carbon T shallbe with the limits .18 to .86%.

We have found that when the chromium or molybdenum concentration isinthe lower end of the range set out above, it is preferable that themanganese concentration approach the upper end of the limits set outherein-above in order that the resulting alloy have the most desirableproperties. The machining properties of the alloy are varied by varyingthe sulphur within the range set out hereinabove, the higher sulphurcontent promot ing better machining as well as reducing the cost offorming dies for the various purposes to which this alloy may beapplied.

While we have given certain limits with respect to the concentration oftungsten and nickel which may be present, their presence is notnecessary and in our preferred composition these elements are absent.However, their presence is optional and may be desirable for certainpurposes within the ranges set out above.

Inorder to illustrate the peculiar adaptability of the present alloy foruse as hot working dies for forging extremely hard and diflicultmaterials, several dies were formed of the preferred composition. Thesedieswere used alongside dies made from conventional alloys. The dieswere used to forge turbine blades from high alloy compositions, as, forexample, Nimonic alloy. The dies were operated until a satisfactoryproduct no longer could be obtained from the dies. It was found that thedies made of the composition of the present invention produced more thanfour times as many pieces, as the conventional alloys. A die made of thealloy of the present invention produced approximately eight-thousandpieces from Nimonic 80 alloy, whereasa conventional die produced onlyabout two-thousand pieces. Other comparative tests of the same typeusing other high alloy materials showed a comparative life of four toten times greater in dies made from the present alloy as compared withdies made from conventional alloys.

It is evident that the advantage of the present alloy as respects to diecost alone is very great. However, the true economic importance of thisresult becomes more apparent when it is realized that the cost in laborand lost time in changing dies is almost as great as the cost of thedies themselves so that an increase in die life of four times actuallyrepresents a saving of approximately eight times in over-all productioncosts. This is a very significant saving in the cost of producing hightemperature super-alloy parts for turbines, jet engine parts and thelike.

While we have illustrated and described certain preferred embodiments ofmy invention, it will be understood that the invention may be otherwiseembodied within the scope of the following claims.

We claim:

1. An alloy adapted for forming metals at high temperatures comprisingabout 0. 65% to about 3.0% carbon, about 3.0% to about 10.0% vanadium,less than about 2% manganese, about 3.0% to about 8.0% chromium, up toabout 2% tungsten, about 0.50% to 3.0% molybdenum, up to about 2%silicon, up to about 3% nickel, up to about 0.25% sulphur and thebalance substantially iron with residual impurities in ordinary amountsin.

vanadium 1 is within the limits of about 0.18% to about 0.86%.

2. An alloy adapted for hot working applications comprising about 1.10%carbon, about 4.0% vanadium, about 0.4% manganese, about 5.25% chromium,about 1.10% molybdenum, about 1.0% silicon and the balance substantiallyiron with residual impurities in ordinary amounts.

3. An article for forming metals at high temperatures formed from asteel alloy comprising about .65% to about 3.0% carbon, about 3.0% toabout 10.0% vanadium, less than about 2% manganese, about 3.0% to about8.0% chromium, up to about 2% tungsten, about .50% to 3.0% molybdenum,up to about 2% silicon, up to about 3% nickel, up to about 0.25 sulphurand the balance substantially iron 'with residual impurities in ordinaryamounts in which alloy the vanadium appears in amounts within theforegoing limits such that the Carbon vanadium- 1 4.2

is within the limits of about 0.18% to about 0.86%, said article beingcharacterized by high resistance to deformation at elevated temperaturesand deep air hardening.

4. A die formed from a steel alloy comprising about "165% to about 3.0%carbon, about 3.0% to about 10.0% vanadium, less than about 2%manganese, about 3.0% to about 8.0% chromium, up to about 2% tungsten,about .50% to 3.0% molybdenum, up to about 2% silicon, up to about 3%nickel, up to about 0.25% sulphur and the balance substantially ironwith residual impurities in ordinary amounts in which alloy the vanadiumappears in amounts within the foregoing limits such that theCarbonvanadium-1 Carbon 4 about 1.0% silicon and the balancesubstantially iron with residual impurities in ordinary amounts, saidarticle being characterized by high resistance to deformation atelevated temperatures and deep air hardening.

5 6. A die for forming metals at high temperatures formed from a steelalloy comprising about 1.10% carbon, about 4.0%vanadium, about 0.4%manganese, about 5.25% chromium, about 1.10% molybdenum,

about 1.0% silicon and the balance substantially iron 'With residualimpurities in ordinary amounts, said die being characterized by highresistance to deformation at elevated temperatures and deep airhardening.

7. An alloy adapted for forming metals at high temperatures comprisingabout 0.65% to about 1.4% carbon, about 3.0% to about 10.0% vanadium,less than about 2% manganese, about 3.0% to about 8.0% chromium, up toabout 2% tungsten, about 0.50% to 3.0% molybdenum, up to about 2%silicon, up to about 3% nickel, up to about 0.25% sulphur and thebalance substantially iron with residual impurities in ordinary amountsin which alloy the vanadium appears in amounts within the foregoinglimits such that the i vanadium 1 Carbon -T is within the limits ofabout 0.18% to about 0.86%.

8. An article for forming metals at high temperatures formed from asteel alloy comprising about .65% to about 1.4% carbon, about 3.0% toabout 10.0% vanadium, less than about 2% manganese, about 3.0% to about8.0% chromium, up to about 2% tungsten, about .50% to 3.0% molybdenum,up to about 2% silicon, up to about 3% nickel, up to about 0.25 sulphurand the 35 balance substantially iron with residual impurities inordinary amounts in which alloy the vanadium appears in amounts withinthe foregoing limits such that the article being characterized by highresistance to deformation at elevated temperatures and deep airhardening.

Carbon References Cited in the file of this patent UNITED STATES PATENTSLuerssen et al. Aug. 8, 1944 Giles Nov. 13, 1951

1. AN ALLOY ADAPTED FOR FORMING METALS AT HIGH TEMPERATURES COMPRISINGABOUT 0.65% TO ABOUT 3.0% CARBON, ABOUT 3.0% TO ABOUT 10.0% VANADIUM,LESS THAN ABOUT 2% MANAGNESE, ABOUT 3.0% TO ABOUT 8.0% CHROMIUM, UP TOABOUT 2% TUNGSTEN, ABOUT 0.50% TO 3.0% MOLYBDENUM, UP TO ABOUT 2SILICON, UP TO ABOUT 3% NICKEL, UP TO ABOUT 0.25% SULPHUR AND THEBALANCE SUBSTANTIALLY IRON WITH RESIDUAL IMPURITIES IN ORDINARY AMOUNTSIN WHICH ALLOY THE VANADIUM APPEARS IN AMOUNTS WITHIN THE FOREGOINGLIMITS SUCH THAT THE